Middleware Creation for GraphQL

package utils
import (
    "net/http"
    "strconv"
    "strings"
    "time"
    "github.com/golang-jwt/jwt/v4"
)
// TokenMetadata represents JWT token metadata
type TokenMetadata struct {
    Expires int64
    UserId  string
}
// ExtractTokenMetadata extracts JWT token metadata
func ExtractTokenMetadata(r *http.Request) (*TokenMetadata, error) {
    // verify the JWT token
    token, err := verifyToken(r)
    // if verification is failed, return an error
    if err != nil {
        return nil, err
    }
    // get a JWT claim from the JWT token
    claims, ok := token.Claims.(jwt.MapClaims)
    // check if the token is valid
    var isValid bool = ok && token.Valid
    // if the JWT token is valid, return the JWT token metadata
    if isValid {
        // set token expiration
        expires := int64(claims["exp"].(float64))
        // set user ID for the token
        userId := claims["userId"].(string)
        // return the JWT token metadata
        return &TokenMetadata{
            Expires: expires,
            UserId:  userId,
        }, nil
    }
    // return an error
    return nil, err
}